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TO-247N(-4L) Half-Bridge Evaluation Board
User’s Guide
© 2022 ROHM Co., Ltd.
No. 63UG0
60E
Rev.001
2022.2
On the other hand, by connecting the mirror clamp signal (MC signal) of the driver IC (BM61M41RFV-C), which is one of the
protection circuits, the surge at turn-off can be suppressed. However, since the MC signal needs to respond at high speed, the
wiring length to the MOSFET should be made as short as possible. The mounting position of the gate resistor for speed
adjustment R
G_EXT
, etc. has priority, and it may not be possible to mount it near the MOSFET, so the clamping effect may not be
sufficient depending on the layout. Based on experience, the clamping effect becomes extremely low when the distance is 20
mm or more.
Therefore, by placing the clamp SBD directly under the MOSFET and adding a circuit that suppresses negative surges (MC
Clamp SBD), the surge suppression effect can be further enhanced, and it can be seen that the gate surge voltage is
suppressed to within the rating in this measurement.
As shown above, surges linked to the transient operation of the MOSFET are generated at the gate pin in both positive and
negative directions, so it is important to place a protection circuit near the MOSFET from the design stage.
12. Precautions
Since this evaluation board handles voltages of several hundred volts, care must be taken at all times to avoid dangerous
situations due to malfunctions. Defects may occur not only in this board, but also due to incorrect handling, such as
misconnection of wiring or application of out-of-specification voltages.
Table 8 shows the points to pay attention to, but please take all possible measures to prevent other problems before
using the product.
Table 8 List of typical faults
Function
Items
Details
DCR
LED does not light
up
When voltage is applied to the HVdc-PGND pins, check that LED301 (red)
is lit. If the LED does not light up, check the applied voltage source and
wiring.
The LED lights up when the input/output voltage is approximately 20 V or
more.
HVdc
Vsw
Misconnection of
wiring
Application of out-
of-specification
voltage
It is strictly prohibited to apply a voltage higher than the specified value
(1200 V), and care must be taken to ensure that there is no misconnection
of wiring, etc. Also, never touch the product while it is in operation.
Vcc
Misconnection of
wiring
Application of out-
of-specification
voltage
Check the wiring of Vcc before use to prevent the application of positive and
negative reverse voltages. However, since a diode for reverse connection is
included, the OPC setting of the Vcc power supply should be set to 1 A to 3
A. (To protect the diode for reverse connection).
Also, applying a voltage other than the specified voltage may cause a
failure, so operate the circuit only after thorough confirmation.
SNB
RDC_SNB
MLCC burnout
An MLCC, that is prone to cracks and other short-circuit failures due to
mechanical stress, is used. Therefore, handle the board with care to avoid
excessive shocks.
If you have even the slightest concern when voltage is applied, immediately
take measures to avoid danger, such as cutting off the applied voltage.
IN_H_CLK
IN_L_CLK
Continuous pulse
application
Continuous application of the CLK signal to drive the DUT may cause a
current exceeding the specified value to flow and may damage the DUT.
Therefore, always use the DUT within the range that satisfies its electrical
characteristics.
DUT
Driver IC damage
If the gate-source of the DUT is short-circuited and the CLK signal to be
driven is turned on, a short-circuit current will flow from Vcc2 through the
OUT pin to GND2, which may destroy the OUT pin of the driver IC if the
external resistance is small. Therefore, be sure to check the gate-source
short circuit conditions before operation.
